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|Title:||Identifying historical flood deposits in a sediment cores|
|Publisher:||Australiasian Quaternary Association Inc.|
|Citation:||Lintern, A., Leahy, P. J., Deletic, A., Gadd, P., Heijnis, H., & McCarthy, D. Identifying historical flood deposits in a sediment cores. Paper presented at the AQUA Beinnial Meeting, The Grand Hotel, Mildura, 29th June - 4th July, 2014.|
|Abstract:||River floods are a risk, not only because of the large volume of water that is mobilized, but also because of the potentially high level of nutrients and pollutants contained in these waters. There is limited understanding of flood water quality, which hinders the implementation of appropriate mitigation strategies. Therefore we must better understand the trends in flood water quality to protect society and the natural environment from risks associated with poor quality flood waters. Fluvial flood water quality data could be obtained using sediment cores from floodplains, as sediment cores can preserve historical flood deposits and can also be used to infer long term trends in the water quality of aquatic environments. This presentation aims to identify and separate flood-deposited fluvial sediments from in-situ biogenic sediments in a sediment core from a floodplain lake, and to then identify the pollutant levels contained in these flood-deposited sediments. The Yarra River (South-East Australia) and its floodplain lake (Willsmere Billabong) was used as a case study. Cores taken from Willsmere Billabong were analysed using the ITRAX micro-X-Ray Fluorescence (XRF) core scanner and the optical and radiographic images, magnetic susceptibility and elemental composition profiles were used to infer the sediment type and origins. Using the data obtained from the core scanner, we found that flooding frequency of the Yarra River into Willsmere Billabong decreased in the early to mid-20th century. This is most likely due to increased water extraction with the construction of large reservoirs in the upper river catchment in 1927, 1932 and 1957. Indeed, there is also a decrease in measured flow rates for the Yarra River. Having identified the flood-deposited sediments within the Willsmere Billabong sediment cores, we have determined pollutant levels within the flood-deposited sediment layers, to identify water quality trends in river flood water quality.|
|Gov't Doc #:||7942|
|Appears in Collections:||Conference Publications|
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